1. Field of the Invention
The present invention relates to a drive system switching control method of an automotive four-wheeled vehicle which can switch between two drive systems comprising a two-wheel drive and a four-wheel drive.
2. Description of the Related Art
With respect to a switching apparatus of an automotive four-wheeled vehicle which can switch between two drive systems comprising the two-wheel drive and the four-wheel drive, the drive system is normally switched by always connecting one of either the front wheels or the rear wheels to a drive source and switching another thereof based on engaging and disengaging a clutch mechanism.
In order to engage and disengage the clutch mechanism, there is an example in which a driver manually engages and disengages the clutch mechanism. See Japanese Patent Application Laid-Open No. 2000-264091 reference document 1. There is another example in which an electromagnetic coil or the like engages and disengages the clutch mechanism. Japanese Patent Application Laid-Open No. 2001-260694 reference document 2.
The former reference document 1 corresponds to a prior application filed by the same applicant as the applicant of the present application. The structure is made such that the drive system is switched by oscillating an operation lever so as to drive a drive system switching clutch mechanism. However, this document does not disclose a structure for inhibiting the switching operation.
In the latter reference document 2, the structure is made such that an electromagnetic clutch is comprised of a clutch plate and an electromagnetic coil. A drive switching apparatus is operated based on an operation of the electromagnetic clutch so as to connect and disconnect between a drive shaft and a driven shaft and switch the drive system. However, with respect to the control of the electromagnetic clutch, this document only discloses that the driven shaft is disconnected from the drive shaft when braking the vehicle.
When switching the drive system, since the driven wheel becomes the drive wheel, or on the contrary, the drive wheel becomes the driven wheel, some motion is generated in the traveling vehicle body.
If this motion is generated during a turning travel, an attitude of the vehicle body is affected so as to become unstable. Accordingly, this motion is not desirable.